Nitrous oxide measurements were made in the southern hemisphere (latitude, 42 ¿S to 72 ¿S) as part of the Airborne Antarctic Ozone Experiment (AAOE) in late winter and early spring 1987, covering the altitude range 14--21 km. This paper reports on N2O measurements made by the airborne tunable laser absorption spectrometer (ATLAS), which was flown on board the NASA ER-2 aircraft. Average vertical N2O profiles at latitudes 72 ¿S, 54 ¿S, and 42 ¿S are presented and compared, when possible, with equivalent summer profiles. Latitudinal gradients of N2O on isentropic surfaces are presented and discussed in terms of their implications about the inhibition of horizontal mixing near the polar vortex. Finally, a large-scale distribution of N2O for the region 72 ¿S to 42 ¿S latitude is presented. The reader is directed to the note added in proof regarding the recent recalibration of this data set. ¿ American Geophysical Union 1989